Electric motor brush holder connection and method for making same



Nov. 11, 1952.

E. L. VERHAGEN 2,617,952 ELECTRIC MOTOR BRUSH HOLDER CONNECTION AND METHOD FOR MAKING SAME Filed Nov. 6. 1950 FIG-.2

u. IIIIIIII/ INVENTOR. Edward L. Verhugen Attorney Patented Nov. 11, 1952 ELECTRIC MOTOR BRUSH HOLDER CON- NECTION AND METHOD FOR MAKING SAME Edward L. Verhagen, Rahway, N. J assignor to The Regina Corporation, Rahway, N. J a corporation of New York Application November 6, 1950, Serial N 0. 194,330

2 Claims. (Cl. 310247) The present invention relates to an electrical connection and more particularly to an electrical connection for brushes of small electric motors.

The object is to provide a novel, simple, inexpensive and reliable electric motor brush holder connection and a method for making the same.

It has been customary in the past to connect the electrical lead to the brush holders by placing a small groove on the outside of the brush holder addition of any additional steps in the assembly of the motor. A brush holder can be constructed embodying the applicants invention with, for all practical purposes, no attendant additional cost of manufacture. It can therefore be seen, that a motor that is much safer in operation can be produced at no additional cost of manufacture.

These and other objects and advantages of the present invention will be more readily apparent and securing a lead thereto by use of a small from the following description and drawing of helical spring. The spring is bent and secured one specific embodiment of the invention, in in the form of a circle and slipped into the groove which drawing: of the brush holder. Fig. 1 is a side view of one end of an electric The natural vibration of the motor while runmotor having brush holders embodying the presning has a tendency to cause the spring and its out invention, in which figure a portion of the electrical lead to rotate on the brush holder. housing has been broken away; This rotation causes displacement of the lead, Fig. 2 is a side view of a brush holder embodyand there is a dangerous tendency for the point ing the present invention; of connection between the spring and the lead Figure 8 is a sectional view taken along line to touch the motor housing causing a short- 33 on Fig. 2 with the spring and lead wire in circuit. position on the brush holder;

Motor brush lead connectors of the type here Fig. 4 is a plan view of the spring and lead; and under consideration are used primarily on small Fig. 5 is a front view thereof. electrical motors of the fractional horsepower The brush holders [0 are secured to rings ll type. Such motors are used in sewing machines, which are formed integral with the end wall 12 vacuum cleaners, floor polishers, and a great of the motor housing. The carbon brushes 13 number of other small electrically operated deare held within the brush holder in close contact vices. Weight and size are prime considerations with the commutator [4. It is customary to proin the design of electric motors of this type and Vids compression springs within the brush holder every effort is made to keep these two features of I0 to urge the brushes [3 into close contact with the motor at a minimum. For this reason the he c m utator u h Co p ess on p s housing is constructed as close as possible to the (not shown) are positioned between the nut I5 motor itself. This results in the housing end and the carbon brushes I 3. The nut I5is threadwall being extremely close to the brush holders. ed into the tapped end I5 of the brush holder ii). In motors of this type, rotation of the spring A ring of insulating material I1 is secured to and brush leads on the brush holder has lead the brush holder on the ou r urf e thereof. to short circuits from two principal sources. and when the brush holder is secured in the First of all when the spring has rotated approxiring H of the end wall [2, the insulator ll promately 180 the point of connection between the vides a complete electrical insulation between the spring and wire lead is very likely to come into e d Wall l2 and the brush holder lfl. contact with the end wall of the housing causing As can best be seen in Fig. 2 the brush holder a short circuit. Another result of the rotation In s pro at One end With o e l8 into of the spring on the brush holder is the displacewhich the helical spring l9 fits. The spr n I!) ment of the wire lead. There is a great danger forms an electrical connection between brushes that this lead will come into contact with the holder 0 and t pr a y Wi ads 0. and commutator. As the commutator rotates at a also acts to secure the leads 2:: to the brush high speed it wears the insulation ofi of the wire holder ID. The brush holder ID is in close elec lead, again causing a short circuit. trical contact with the brushes [3 and therefore One attempt to eliminate this dangerous situathe leads 20 are also electrically connected to tion has been to solder the spring to the brush the brushes 13. The spring [9 is bent int a holder. This obviously adds another step in the loop to form a resilient collar and is secured in assembly of the motor and increases the cost of this position by solder 2!. The solder 2! also production. By using a brush holder embodying secures the primary winding lead 20 to the the applicants invention the rotation of spring spring l9. on the brush holder is eliminated without the Projections 22 are located in groove l8, four of such projections 22 are shown. Of course more or less than that number may be used. The projections 22 within groove I8 form gripping points for the spring [9, and act to prevent the spring [9 from rotating within the groove. The vibration of the motor as it operates tends to cause the spring I!) to rotate about the longitudinal axis of the brush holder 10. It can readily be seen that if the spring 19 rotated far enough so that the soldered connection point were located to the left in Figs. 1 or 3, there would be a great danger that this point would touch the end wall I2 of the casing causing a short-circuit. It is also apparent thatthere is a danger that the primary Winding lead 20 might brush against the commutator with the result that its insulation would be worn off causing a short circuit. It can therefore be seen that the projections 22, by providing gripping points for the spring 16, prevent its rotation, and eliminate this source of dangerous short circuits. 7

As can be bestseen in 3 the brush holders iii are hollow and the rectangular brushes I 3 are held within this hollow opening. The hollow opening is provided with two rectangular portions 23 which extend the length of the brush holder iii. In the manufacture of the brush'h'olde'r these rectangular portions '23 are formed by broaching. The breaching operation at the point directly under the grooves causes the thin Wall of material at the corners of the rectangular portion to be displaced rather than being cutaway; as can be readily appreciated, the wall of the brush holder at this point becomes extremely thin dur- 4 ing the broaching operation, and therefore is easily displaced. In the specific form of the in vention shown in the drawing, the material so displaced becomes the projections 22.

I claim:

1. A brush holder connection for an electric motor which comprises a cylinder of conductive material having a circumferential groove near one end and having a perforation of polygonal cross section extending from end to end, the material of said cylinder being flared outwardly adjacent the corners of said perforation into said groove, and a garter spring partly within said groove and surrounding said cylinder.

2. The methodof making a brush holder connection for an electric motor which comprises forming a circumferential groove near one end of a cylinder of conductive material having an axial bore therethrough, forcing a broach of polygonal cross section through said bore and thereby radially deforming the material of said cylinder within said groove, and surrounding said cylinder at said groove with a garter spring.

EDWARD L. V E RHAGEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,793,258 Smelli Feb. 17, 1931 2,449,764 Bluemink Sept. 21, 1948 2,45%,230 Stickney Nov. i 1948 

